Biassed electrical relays



Oct. ,6, 1970 G. J. ALLEN 3,533,033

BIASSED ELECTRICAL RELAYS Filed June 14. 1968 United States Patent 3,533,033 BIASSED ELECTRICAL RELAYS Graham John Allen, London, England, assignor to Westinghouse Brake and Signal Company Limited Filed June 14, 1968, Ser. No. 736,993 Claims priority, application Great Britain, June 28, 1967, 29,888/ 67 Int. Cl. H01t' 7/08 US. Cl. 335-230 Claims ABSTRACT OF THE DISCLOSURE A biassed, non-stick electrical relay includes a permanent magnet which shunts fluxes produced by an energizing voltage of one polarity away from the armature air gap to prevent actuation of the armature and which repulses fluxes produced by an energizing voltage of the opposite polarity so that these fluxes pass across the armature air gap to cause actuation of the armature.

This invention relates to biassed electrical relays and relates in particular to such relays 'which are biassed to only respond to energisation of one voltage polarity by means of suitably disposed permanent magnet means.

According to the invention there is provided a biassed, non-stick electrical relay comprising a magnetizable core, a coil wound around said core for receiving energizing voltages, a biassed armature biassed to normally provide an air gap between the armature and the core, a magnetizable yoke portion, and a permanent magnet mounted between the core and said yoke portion for cooperating to produce a first flux path which includes the core, the armature, the armature air gap, and the yoke portion and excludes the magnet, responsive to energization of said coil by a voltage of one polarity, to cause actuation of said armature, and for providing a further flux path which includes the core, the magnet, and said yoke portion and which excludes the air gap and the armature, responsive to the energization of said coil by a voltage of the opposite polarity.

By virtue of the invention the magnet may be a single magnet and it may if desired be extended to embrace the core.

Also by virture of the invention, a plurality of such relays may be constructed in conjunction with a single magnetisable yoke a single magnet serving as a said per manent magnet for each of the relays.

Again, the magnet may be provided in conjunction with a shunt of magnetic material embracing the or each relay core and closely abutting the magnetisable yoke.

- In order that the present invention may be more clearly understood and readily carried into effect, the same will be further described by way of example with reference to the accompanying drawing of which:

FIG. 1 illustrates in diagrammatical form a relay pair constructed in accordance with the present invention, and

FIG. 2 illustrates a possible modification of part of the relay pair shown in FIG. 1.

Referring to the drawing, the relay pair of FIG. 1 is constructed upon an L-shaped magnetisable yoke member represented by the reference 1 the base portion of the yoke member carries two cores represented by references 2 and 3 these cores carrying energising windings 4 and 5 for the respective relays of the relays pair. Mounted upon each of the cores substantially co-axially with the windings 4 and 5 are respective copper conducting rings 6 and 7 which provide in known manner for A.C. immunity of the relay. Also embracing each of the cores 2 and 3 above the c0nducting.rings 6 and 7 there are provided soft iron magnetisable shunt members 8 and 9. These are rectangular in shape and the ends thereof remote from the ends of the cores 2 and 3 abut the vertical portion of the magnetisable yoke 1 as shown. Between the upper ends (as viewed in the drawing) of the cores 2 and 3 there is provided a continuous bar magnet which is magnetised in the sense indicated by the polarity markings thereof. As will be seen hereafter this bar magnet serves as biasing means for each of the relays. Further, the relays are each provided with an armature, a portion of the armature of the electrical relay incorporating the core 3 being indicated at reference 11. The remaining armature associated with the core 2 is removed to illustrate more clearly the construction of the relay with regard to the position of the bar magnet 10. The armatures of each of the relays are movable in directions indicated by the arrows 12 and will be understood to be spring biased in the upward direction (as viewed in the drawing) so as to be normally in an uppermost position, by spring biasing means not shown in the drawing. In the lowermost position (as viewed in the drawing) of the armatures of the relays, the armature rests against end pieces such as 13 on each of the cores 2 and 3.

In operation of one relay of the relay pair shown in FIG. 1, assuming that the winding 4 is energised by a direct current supply having the polarity shown and of suflicient magnitude, this induces magnetic flux in the core 3 and since the flux induced by this sense of energisation of winding 4, tends to be in opposition to the polarity of the portion of the bar magnet 10 resting between the member 1 and the core 2, and the shunt portion 8 is saturated, the tendency is for the flux to pass across the air gap between the'core 2 and the armature associated therewith. A flux path therefore is provided through core 2, the air gap, the armature and the magnetisable yoke member 1 and the armature is attracted against the head of the core 2 to operate the contacts of the relay.

In the event however, of the winding 4 being energised in the opposite polarity to that shown, the flux induced in the core 2 now tends to assist the fiux due to the permanent magnet 10 between the core 2 and the magnetisable yoke 1 and substantially all the effective flux flows in the flux path including the core 2, the portion of the bar magnet 10 between 2 and 1 and the yoke 1. There is very little flux across the air gap between the core 2 and the armature and therefore the armature remains in its uppermost position.

The other relay of the pair operates similarly and each therefore is a biassed relay which is unresponsive to energisation in the incorrect sense of the energising windings but is responsive to normal energisation of the correct sense. The conducting rings -6 and 7 moreover render the relay substantially immune to AC. components of energisation applied to the windings 4 and 5 respectively. This immunity is enhanced by the fact that the biassing magnet diverts one half of the AC. flux generated.

The shunts 8 and 9 are by no means essential to this invention but provide for desirable electrical characteristics of the relay and in FIG. 2, there is illustrated a manner in which the single bar magnet 10 may be extended if desired to embrace the cores 2 and 3.

Further, the shunt portions '8 and 9 of FIG. 1 may be formed if desired of a single magnetisable part and if desired in any particular case, suitable slots may be provided in the combined shunt and/or the magnet 10 to reduce magnetic leakage between adjacent cores.

It will be appreciated moreover that varioius modifications of the basic concept of a single magnet which is operable to provide biasing for a plurality of relays, may be achieved within the scope of the present invention.

I claim:

. 1. A biassed, non-stick electrical relay comprising a magnetizable core, a coil wound around said core for receiving energizing voltages, a biassed armature biassed to normally provide an air gap between the armature and the coil, a magnetizable yoke portion, and a permanent magnet mounted between the core and said yoke portion for cooperating to produce a :first flux path which includes the core, the armature, the air gap, and the yoke portion, and excludes the magnet, responsive to the energization of said coil by a voltage of one polarity, to cause actuation of said armature, and for providing a further flux path which includes the core, the magnet, and said yoke portion and which excludes tthe air gap and the armature, responsive to the energization of said coil by a voltage of the opposite polarity.

2. An electrical relay assemly comprising a plurality of biassed, non-stick electrical relays each includin a magnetizable core, an energizable coil Wound around said core, a biassed armature biassed to normally provide an air gap between the armature and the core, and a magnetizable yoke portion, and a common permanently magnetized bar for providing by-pass flux paths excluding the armatures and air gaps of said relays for fluxes in the cores produced by energization of said coils by a voltage of a first polarity, said common magnetized bar cooperating to provide a second flux path which ineludes the armatures and the air gaps of said relays for fluxes in the cores produced by energization of said coils by voltages of an opposite polarity.

3. A relay as claimed in claim 1 further comprising a magnetizable shunt mounted between the core and said yoke portion.

4. A relay as claimed in claim 1 further comprising an electrically conducting member mounted on said core for providing alternating current immunity.

5. A relay as claimed in claim 1 wherein said permanent magnet abuts a portion of the core adjacent said armature.

References Cited UNITED STATES PATENTS 1,792,318 2/1931 IOMeara et al 335230 1,847,339 3/1932 Freeman 335232 1,890,525 12/1932 Martin 335---232 3,109,126 10/1963 Hailes 335234 FOREIGN PATENTS 983,303 2/ 1965 Great Britain.

GEORGE HARRIS, Primary Examiner U.S. Cl. X.R. 335232 

